1. Field of the Invention
This invention relates to the air conditioning and heating art and more particularly to a conditioned air system which is energy efficient utilizing a central source and constant volume controllers in each duct leading to the conditioned spaces.
2. Description of the Prior Art
The typical air conditioning and heating problem encountered in a building concerns the distribution of heated or cooled air from a central source to a plurality of spaces or rooms about the building located at various distances from the central source. Forced air systems blow the heated or cooled air from the central source through ducts out to the various rooms. Air in the duct system always flows most readily through the duct having the least amount of resistance. On the other hand, the least amount of air flows through the duct having the highest resistance. The most basic technique for attempting to equalize the flow to the various locations is to provide large diameter ducts to the remote locations and small diameter ducts to the closer locations. Fine tuning of the duct system can be then achieved by locating dampers at the ends of the ducts which may be adjusted to produce the desired result. However, at varying times during the day, the heating and cooling requirements in the various locations in the building change producing problems which are not solved in the most basic system and result in great energy inefficiencies.
Another problem inherent in most air conditioning and heating systems is that one thermostat at one location in the building controls the production of heated or cooled air by the central source. Again, variations in different portions of the system at different times of day often create conditions which cannot be satisfactorily solved by the use of a single thermostat for the central source.
Some systems have been designed incorporating various degrees of sophistication to provide the desired amount of heated or cooled air to a given room from a remote central source. The systems generally utilize constant volume flow controllers operating dampers located in the various ducts which are responsive to fluid flows through the particular ducts and temperatures in the rooms being conditioned. These constant volume controllers are subject to breakdown because of the complexity of the physical parts and inefficient because of the failure to coordinate with the heating or cooling output of the central source that is determined by a centrally located thermostat. In addition, the majority of the control systems operate best at a desired average level and are unable to cope adequately with extreme conditions which require rapid heating or cooling to achieve satisfactory conditions in a short time.
Another problem often encountered in constant volume controllers is the inability to measure turbulent flow conditions such as are encountered at corners and divisions. Continuously high or low fluid flow problems result.